Project Summary/Abstract Although overall annual HIV incidence in the United States (US) has declined in recent years, the rate of new infections remains stable specifically among men who have sex with men (MSM). A once-daily antiviral drug (emtricitabine/tenofovir) has recently been approved in the US for use as HIV pre-exposure prophylaxis (PrEP), and could offer an important pathway for achieving a sustained decline in new HIV infections among MSM. However, its effectiveness depends on sufficient adherence and persistence to the drug. A robust literature shows that heavy drinking disrupts adherence to similar medications when used for HIV treatment, resulting in onward transmissions and poorer health outcomes among those living with HIV. Our ongoing work shows that heavy drinking days occur more frequently during lapses in PrEP adherence that are sufficient to reduce its effectiveness (4+ days of missed doses) than periods with more consistent adherence, suggesting that heavy drinking may similarly affect adherence to PrEP. Meta-analyses show that brief interventions can help many at-risk individuals reduce their alcohol use and adhere to antiviral drugs prescribed for HIV treatment, even when these interventions are delivered via computer. Moreover, some of the more robust effects on these outcomes have been demonstrated for interventions based on the Trans-Theoretical Model of Change (TTM) or that were inspired by Motivational Interviewing (i.e., brief motivational interventions [BMIs]). Brief, computer-delivered interventions like these also have a number of advantages in terms of scalability, cost, and feasibility of implementation into resource-constrained clinical settings. We recently developed a tablet-optimized, internet-facilitated BMI called Game Plan that was designed to help high-risk MSM in HIV testing clinics reduce their alcohol use and sexual risk (R347AA023478). Preliminary data shows that this intervention encourages non-treatment-seeking MSM to set drinking-related change goals and ultimately reduce their drinking in the months following intervention. The proposed research will support the development of a similar intervention, called Game Plan for PrEP, that is intended to help heavy drinking MSM on PrEP reduce heavy episodic drinking and adhere to/persist with PrEP. Specifically, we will (1) employ user-centered design methods to help design and develop a tablet-optimized, internet-facilitated intervention that addresses these goals by drawing on the perspectives of intended users, as well as existing alcohol BMIs and medication adherence interventions. We will also (2) conduct a small randomized-controlled pilot study exploring the intervention?s effects on biomarkers of alcohol use and PrEP adherence over a 6-month period. If results are supportive, this research will produce one of the first scalable brief interventions addressing alcohol use in the context of PrEP care. Future research can explore the intervention?s effects in a full-scale randomized control trial, as well as its mechanisms and approaches for boosting its effects on key outcomes.